Among systemic therapies of renal cell carcinoma, only cytokine therapies using IFN-α and IL-2 had been found effective, though the effect was very small. However, since the molecular target drugs sorafenib and sunitinib were approved as therapeutic agents for renal cell carcinoma in Europe and the U.S., they have begun replace cytokine therapies as standard therapy of renal cell carcinoma.
However, Non-patent Literature 1 to 3 discloses that the clinical performance of those molecular target drugs (with respect to the patients in which cytokine therapies had no effect), namely, 10 to 36.5% response rate and 5.5 to 8.7 months median progression-free survival (PFS), are lower than in other cancers. Moreover, Japan has a poor record regarding practical accomplishment in medical care with molecular target drugs, and the effectiveness and the safety of molecular target drugs are not fully confirmed. Therefore, it is necessary to verify their effectiveness and safety.
In addition, in 1995, Yagoda et al. reported a general overview of the effectiveness of systematic therapies for renal cell carcinoma mainly using anticancer agents. Yagoda summarized 83 clinical test results, and disclosed that the response rate of the most effective agent, namely, 5-fluorouracil (5-FU) or floxuridine, was 13.4% (Non-patent Literature 4). In 1990s, studies mainly focused on floxuridine; however, no effect superior to that of cytokine therapies has thus far been confirmed (Non-patent Literature 5).
As such, a therapeutic system for renal cell carcinoma has not yet been established in Japan, and a standard therapy therefor has not yet been discovered. Further, even after manufacturing approval of the two molecular target drugs, patients have few treatment options, and the therapeutic circumstances of renal cell carcinoma patients are still not satisfactory.